This invention relates generally to bearings, and more particularly to a bearing mechanism which is usable in personal transport devices including in-line skates, skateboards and scooters.
Recently, personal transport devices, including in-line skates, skateboards, scooters and other similarly wheeled vehicles, have become very popular in the United States, Asia, South America and Europe. The company Roller Blade of Minnesota popularized in-line skating during the 1980s and 1990s. Skateboards also became very popular, particularly on the West Coast of the United States. Recently, the Razor scooters have become extremely popular, not only in the United States, but throughout China and other countries where scooters are used as a form of primary transportation. These three applications use the same wheels, and consequently the same bearings.
Needless to say, the wheels on these wheeled vehicles are very important for their performance. These devices, especially the in-line skates, use a dual-bearing configuration on each wheel. With regards to performance, the bearings are the most important part of the wheel, and are crucial for the speed and reduction of friction, two important aspects of the performance. Some of the wheels and bearings utilize steel balls in the ball bearings, while the more expensive ones use ceramic balls. Ceramic ball bearings outperform steel ball bearings significantly. Regardless of the balls used, the bearings conventionally consist of a grooved inner ring, or inner race, and a complementary grooved outer ring, or outer race. The balls are held within the grooves, and the inner and outer races rotate about one another.
The wheels themselves are conventionally a cast polyurethane structure around a hard plastic core. The hard plastic core is generally referred to as the xe2x80x9cwheel hubxe2x80x9d, and this hub includes pockets or recesses in the hard plastic core act to receive the roller bearings on either side of the core. These bearing recesses are symmetrical about their axis, and the bearings received therein are substantially identical, working best when they are in a substantially parallel configuration, with the axle being as perpendicular as possible to the parallel bearings.
As one can imagine, uneven loads on the bearings deter the performance of the wheeled vehicle, such that it is a constant task by the owners to re-adjust the bearing pressure in order to hold the bearings in proper placement within the bearing recesses of the wheel hub. It would be advantageous if there were a system to hold the bearings on either side of the wheel hub in an essentially perpendicular fashion to the axle of the wheel, evening out the load and optimizing the pressures.
Attempts to hold the bearings flush to the wheel hub so that the forces are perpendicular to the axle have resulted in mixed success. Some companies have tried to improve the bearings themselves, while others have tried to utilize caps, flanges, rings and the like for holding the bearings in place within the hub. To prolong performance, shields have been used on the xe2x80x9coutsidexe2x80x9d and xe2x80x9cinsidexe2x80x9d surfaces of the bearing races in order to prevent dirt and grime from entering into the cavity where the ball bearings are held. These xe2x80x9cshieldsxe2x80x9d have had some modicum of success in preventing grit, dirt and grime which is always present on the sidewalks and roadways on which these wheeled personal transport devices are utilized.
It is general knowledge that the roadways and sidewalks on which these in-line skates, skateboards and scooters are utilized have road grime and dust which will impede the rolling of the ball bearings if the road dust gets between the ball bearing and the groove which holds the ball bearing inside the bearing races. Consequently, it would be a great advantage to have a bearing system which held the ball bearings in their proper place for maximum performance, while allowing for the shields to be used to prevent dirt and grime from entering the bearing race itself. Furthermore, it would also be advantageous if such a bearing system had an interchangeable, inexpensive part which would allow for the use of the same bearings to be used on many different applications.
For instance, a skating enthusiast may decide to spend the extra money for a set of ceramic ball bearings, which can be approximately three to ten times the price of inexpensive steel ball bearings. That skating enthusiast would also want to be able to use those same ceramic bearings not only on their in-line skates, but also on their skateboard, scooter or their hockey, speed, or artistic skates as well. However, the bearings are not all the same size. For example, the ball bearings used on a skateboard typically has an inner diameter of about 8 mm, while fitness in-line skates have an inner diameter of 7 mm, hockey skates have an inner diameter of either 8 or 6.4 mm, while speed skates utilize an inner diameter of 8 or 7 mm. Artistic skates vary across the board. It would be most advantageous to be able to interchangeably utilize these expensive ceramic bearings for all of these applications. Prior to the present invention, each of these different applications required a different set of ball bearings for fitting into the bearing recesses in the wheel hub.
Regardless of the application, the inner race of the ball bearing must stay as stationary as possible in order to achieve maximum performance. Uneven pressures on the bearings cause them to rotate and twist, which causes undue pressures at various angles. As mentioned above, in-line skating enthusiasts have needed to xe2x80x9csnug downxe2x80x9d the bearings, and continuously re-adjust them as their skating makes the bearings out of alignment.
As mentioned above, these personal transport device applications usually use two bearings for each wheel. Upon reviewing the physics and motion of the bearings, it can be seen that the two bearings will operate at their optimum performance when the bearings are as close to parallel as possible, with both of them being perpendicular to the axis of the wheel hub. Then, the friction of the balls within the grooves of the races will be at a minimum. Everyone will agree that it is best for the ball bearing to be free rolling instead of being bound up by friction.
Prior art methods for adapting these wheels to the various devices mentioned above have included the use of washers, spacers, and all sorts of other arrangements to adapt an axle to a particular bearing. Tightening and loosening the axle to adjust the perpendicularity of the bearings with respect to the axle will result in side loads on the balls which inhibit rolling action. Uneven loads generally result in constantly re-adjusting the axle pressure on the bearings themselves.
Therefore, the present invention is directed towards the creation of a complete bearing system or mechanism which will not distort the bearing races from their optimal perpendicular alignment with respect to the axle, while providing a bearing system which will transmit even loads to the bearings without jeopardizing the performance. Furthermore, it is recognized that it would be most advantageous to include a bearing system which will keep the inner race of the bearing as stationary as possible so that re-adjustment is not necessary as before.
In order to meet these and other objects and advantages, the present invention provides a complete bearing mechanism which includes certain essential features, including a ball bearing configuration, preferably having nine ball bearings, but which may include seven or more bearings, an inner sleeve for holding the inner race of the bearings steady, and two bearing caps which include flanged structures for receiving an axle therethrough. The bearing cap flanges apply pressure on the outside surfaces of the inner race of each of the bearings, thereby exerting equal pressures from both sides of the inner race against the ball bearing in order to maintain even pressures and loads thereon. This bearing mechanism is to be inserted into a wheel within the wheel hub and to be captured within bearing recesses in the hub, found within the cast urethane wheel itself. Once assembled, the first and second bearing caps hold the bearing races in place within the bearing recesses, while the inner sleeve acts to hold the inside surfaces of the bearing races in proper alignment and position to maximize and optimize the alignment of the bearings within the wheel hub itself.